<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdn.bootcss.com/vue/2.6.10/vue.js"></script>
</head>
<body>
    <div id="app">
        <p>{{msg}}</p>
        <button @click="handleClick">toggle</button>
    </div>
    <script>
       var app=new Vue({
           el:"#app",
           data(){
               return{
                   msg:"hello world"
               }
           },
           methods: {
               handleClick(){
                   this.msg="good"
               }
           },
       })
    </script>
</body>
</html>